In conventional fluidized beds, air (or some fluidizing gas) is passed upward through a chamber containing a bed of fine particles at pressure velocity sufficient to force these particles to move and tumble inside the chamber resembling the boiling action of a liquid, hence the name fluidized bed.
During operation of a fluidized bed used as a combustor or furnace these bed particles are pre-heated to some pre-determined temperature, usually several hundred degrees above the kindling point of the fuel to be used in combustion, then said fuel is introduced or fed into the combustion chamber (or bed) where it is ignited by coming in contact with the bed material and burned with the fluidizing air to release heat. Burning fuel in this manner has shown numerous improvements or advantages in the combustion process in terms of: (1) increased efficiency in capture of available BTUs per pound of fuel; (2) allowing us to burn low quality fuels (high ash fuel) (i.e. by-products from a variety of industrial and agricultural processes); (3) allowing a smaller combustion chamber design per given BTU output; (4) allowing fuel to be burned efficiently at lower temperature which decreases the pollution generated; (5) allowing multi-fuel capability within one furnace design; (6) allowing us to capture by-products of the combustion process and poisons laden in some fuels, in the bed material which has led to the discovery that chemical poisons (i.e. toxic waste) can be burned in a fluidized bed where said poisons are captured and civilized in the bed material. But heretofore fluidized bed combustors and the like are huge cludge or equipment and as yet fluidized bed combustors and the like are still a rarity in our society because of their sophisticated design and apparent anonymity. Therefore, improvements in fluidized beds are a much needed discovery during this time of energy conservation and environmental protection, especially from toxic pollution and waste disposal.